Controller deviation recorder



Aug. 13, l 1940. 4nz. J. `BRowN 2,211,317`

GONTROLIJSR` DEVlATION RECORDER Filed July 16, 1937 2 Sheets-Sheet 1 7U CON TROL MOTOR new cow-ANT SPEED ATTORNEY Aug 13 l940- c. J. B RowN, 2,211,317

CONTROLLER DEVIATION RECORDER Filed July l5, 1937 I 2 Sheets-Shea?. 2

Patented ug.' 13, 1 940 lUMTED STATES PATENT OFFICE 2,211,317 CONTROLLER DEVIATIQN RECORDER Cuthbert J. Brown, Foxboro, Mass., assignor to The Foxboro Company, Foxboro, Mass., a corporation of Massachusetts Application July 1c, 1937, serial No. 153,965

4 claims. (01.234-70) cording variations in a condition, such for example, as temperature, it has been found desirable to accomplish these results with separate instruments in order that each instrument might be designed to do its/ particular task with'the utmost efficiency. Attempts to combine these functions into one instrument have been generally unsatisfactory, either the accuracy of the record or the range andvsensitivity of the control suiering by .the combination. It is desirable, however, for the satisfactory operation of a controller to have a record of the control affected thereby so that adjustments to the control device may be made intelligently, and it is important that the apparatus for producing such a record does not interfere with the controlling operation. Accordingly, `itis an object of this invention to provide apparatus for recording the control obtained by a controller, which apparatus does not interfere with the operation of .the controller.

This, and other apparent objects and advantages are obtained by the means described in the following specification, and may be more readily understood by reference to the accompanying drawings in which:

Figure l illustrates in perspective an embodi- Ament of the invention;

Figure 2 is a plan View of the recording portion of the apparatus shown in Figure 1;

Figure 3 is a vertical section on line 3--3 of Figure `2; and

Figure 4 is a vertical `sectionof a frame adjustment member taken on line 4--4 of Figure 3.

Referring to Figure 1, a fportionl of a controller mechanism is generally indicated at I, and a recorder mechanism for recording the deviation from -a predetermined value of'the condition affected by controller'l is generally indicated at 2. A galvanometer or meter element 3 responsive to the value of a condition, such as temperature, is suitably connected to an electrical condition responsive 'circuit (not shown)v which is so adjusted that the galvanometer pointer 4 is at the zero point of a suitable scale I when the condi tionis at the desired value. Variations of the condition causethe pointer 4 to move over scale III. The position ofthe pointer 4 is transmitted through a suitable feeler' mechanism, such for example as that described in the U.-S. patent application No. 281,626 to C.' E. Mason et ai., whicn is more or less diagrammatically illustrated at 20, to position a rocker arm I6 attached to a Y v shaft I1 in a rotational position corresponding to the position of the galvanometer needle 4 with respect to scale I0. The angular position of shaft II determines the position of a fiapper member 5 of a pneumatic control couple 6, such as shown in the above mentioned patent application and in the U. S. Reissue Patent No. 20,092 to C. E. Mason, and the. pneumatic couple 6 `together with other mechanism not here shown but disclosed in said] reissue patent operate a suitable pneumatic motor adapted to control an agent -iniiuencing .the condition afiectingpointer l 4. This control couple t and its associated control mechanism is preferably made sensitive tov l slight changes in the position of the pointer 4 and thus to slight changes in the value of the condition being controlled.

The feeler mechanism 2d is so designed as to cause the position of rocker arm i6 and flapper I5 to follow closely the position of pointer 4. The' feeler mechanism more or less diagrammatically illustrated at is driven-by a constant speed motor (not shown) which drives a shaft 8 rotat' ing a cam 9 attached thereto. Cam 9, through suitable mechanism operates a series' of members i I, l2, and i3 of the feeler mechanism 20 :to periodically position the rocker arm i6 in an angu- .lar position corresponding to the position of pointer il. The .members il, I2, and I3, which may be termed a clamping member, a detector member, and a depressor" member, respectively, are each rotatably mounted on a shaft I 8. A cam follower .202 is rotatably mounted on la pin 20d secured to an extension 206 of the depressor member I3 exten-ding to the right oi? shaft'l. A Wegiht 20d on the left-hand end of member I3 holds cam follower 2M in continuous contact with the cam surface oi cam 9 so that the member i3 is periodically oscillated up and down as the 'cam 9 rotates. A pin 2m projects from the left-hand end of member I3 under the left-hand end I4 of detector member I2. As member i3 moves upward, pin 2 It picks up mem# ber I2 and carries it along, thus imparting a corresponding rnotion to member i2. Member I2 is biased by a spring 2li! so that its left-hand end yit is normally urged. downwardly to contactpin dit on member iii. .a fpln till is secured to an extension 2id on the right-hand end of member i2 and projects into the path ci an e, tension 2I8. on the right-hand end of clamping ember II. A spring 220 is provided to normally hold'extenwise rotation carrying member I2 along with i-t until pinv 2I4 contacts extension y2li! of member -I I, thus imparting to member I I a clockwise mo- -tion so that all three members II, I2, and I3 move to Ythe limit of their clockwise travel. As

cam follower 282 passes its lowermost position and starts to rise, 'members II, I2, and I3 rotate in a counterclockwise direction so that their left-hand ends descend. As they descend, clamping member II contacts pointer 4 and clamps it against an anvil I8 horizontally disposed behind the scale l0. Pin 2I4 then leaves extension ZIB of member II, and members I2 and "I3 continueV to descend until the motion of detector member 1l 2, which has a calibrated curved contacting edge., onl its underside, is arrested by contacting pointer 4. The curved lower edge of member I2 caus it to assmne an angular position about shaft I8 which corresponds-'to the position of pointent with respect to scale Ill and its left-hand end' I4 assumes a vertical position which is in proportional correspondence to the horizontal position of pointer 4 with respect to scale I8. If, in assuming this vertical position, the end -I 4'of inember I2 contacts the left-hand'end I5 of rocker arm I6, it carries end AI5 with it to the extreme of its motion, thus causing shaflt I'I to rotate and assume an angular position corresponding proportionally'to the position of pointer 4. If the .left-hand end I4 of member I2 doesnot contact end I5 of rocker arm I6, then depressor member I3, which continues to descend after thev motion .of detector member I2 is arrested by contacting pointer 4, :contacts the right-hand end 1 of rocker arm I8 andforces it downwardly until the lefthand end I5 of rocker arm I6 contacts the endv of detector member I2. Thus, the action of either the free end I4 of detector member I2 against end I5 of rocker arm I6, or the freeend of depressoimember I3 yagainst the other end 'I of roc-ker arm I6,v causes' shaft I'I to assume an angular .position corresponding proportionally to the position of pointer 4, whether, immediately precedingktl'lis peration of the feeler mechanism, the end I5 of rocker arm Iiiy is a'bove or below the vertical position to be assumed by the free end I4 of detector member I2 after each periodic operation of the feeler mechanism 28. This operation is continued periodically as cam 9 rotates, alternately, freeing pointer 4, then clamping it, detecting its position, and positioning rocker arm shaft II in angular correspondence to its position. Shaft II is frictionally supported between a resiliently mounted friction-creatingthrust bearing 22 and an adjustable pivot bearing I9, so that it remains i'n its last succeeding positionuntil the next periodic operation of the arms II, I2

and I3. An arm v2l is lattached to shaft I1 and thus is also positioned in correspondence to the position of needle 4. 'This arm 2| provides a connection to apper member 5 of control couple `Ii and it is also connected by -a wire link 32 to the deviation recorder mechanism 2. provided in'end I5 of member I6, and a weight 24 is mounted on the other end 1 of member I6. Proper pioportioning of the size of this hole 23 and the mass of weight .24 permits accurate counterbalancing f the flapper-moving mecha- A hole 23 is' nisin including member I6, shaft I1, arm 2I, pin` 2 5, resilient connecting member 26, and apper 5.

ports the strip chart 54. Frame 36 is pivotally 1 mounted at 98 to the base of the instrument lcase between the arms 33 and 35 in such a Almanner that it may be tipped forward to a.

readily 'accessible position for renewing the strip chart.

A U-shaped .,shaft 44 is pivotally mounted on yframe v34 ata point 48 in the upper left-hand `corner thereof and on the forward portion of -arm 33 at a point 46 on the same horizontal axis as pointfill. An arm 38 is rigidly attachedto shaft 44 and extends therefrom on both sides of the pivot point v40. One end of armv 38 is connected'to arm'2i of the controller mechanism I -by wire link 32, and the other end is provided -with' a Counterweight 42. An arm 48, extending downwardly, is also pivoted at 46 and is adjusta'bly secured with respect to the U-shaped shaft 44 by ariV adjustment screw arrangement 58 whereby the angular position of arm 48 with respect toshaft 44 may be adjusted as desired. A horizontal orossbar or pen rack 52 extending -a'crossthe'front of the frame 36, is -detachably -pivoted to the lower extremities of lever 48 and a wire link 58 which depends, parallel to lever 48, from a point on arm 35 in the same horizonltal plane as point 48. The detachable mounting of pen rack A52 is such that the rack is freely disengaged from the arm 48 by merely lifting the slot in 'crossbar 52 from its connection with a headed stud 49 provided in the end of the arm v48. Thus, the pen may be removed for cleaning Ipurposes or for the purpose of renewing the chart without disturbing the control mechanism I. A box type pen 56 is separably mounted at the cen- -te-r of pen rack 52 and this pen, thus supported, moves 'across the strip chart 54 in response to movement of the galvanometer needle 4 and thereby makes a record of such movement.

Counterweight 42 is so designed and so mounted that the center of gravity of the movable linkage assembly is approximately in the axis of the pivot points 40 and- 46 throughout its range of i operative movement.

A lever 60, attached to cam 9 on drive shaft 8 at an oi-center point 62, operates a pawl and ratchet member 54 to rotate a drive-shaft 66 mounted on arm 35 of frame 34. Drive shaft 66, through a worm-gear 68 and a pinion Ill, rotates a shaft 1.2 mounted on the arm 35 and on an arm 31 extending parallel to arm 33 of frame 34 in suitable bearings 'I6 and 18, respectively. A floating shaft 88 is rotatably mounted parallel to shaft 'I2 on the arms of a U-shaped frame 98 across the base of .the U. The ends of this frame 98 Swingin suitable bearings on shaft 'I2 so that shaft 88 may oscillate about but always remain parallel to shaft 12; and a gear 88, mounted on 'shaft 1'2, always meshes with and drives a gear 8,4 secured to floating shaft 88. Two rubber drive rolls as are attachedh to shaft as and are pressed against the strip chart 54 wound upon a windup roll II6 by'a spring 92, which spring is wound around a shaft |36 extending across frame 9U paraiiel to shafts 12 and sa. The ends of spring =9`2 react respectively against frame 34 and frame Suso yas to' urge the drive rolls 86 upwardly tated a certain' number of revolutions in a given time interval,. and as they always act on the surfce of the chart, this arrangement drives the strip ch'art at a constant speed. In addition, the rubber drive rolls 86 are free to move gradually downward away from theaxis of the wind-up `roll ||6 as the diameter o f the roll increases as the strip chart is rolled thereupon Without, however, interfering with the paper drive action'.

A knurled knob |38 is provided on the forward end of drive shaft 66 to advance the strip chart 54 manually when desired.`

The record strip frame 36 comprises two vertical parallel guide plates `94 and 96 spaced apart by suitable separation members a distance equal to the width of the strip chart 54 so thatl these plates act as guides to keep the strip chart in alignment as it advances past the pen 56. This frame 36 is pivotally attached at points 98 near the lower forward corners of side plates 94 and 96 to a U-shaped member |00 attached to the frame 36 as the strip chart unwlnds.

the base of the instrument case so that-frame 36 maybe swung out away from the rubber drive rolls 86 for ready access when replacing.

the chart. 'Ihe strip chart feed roll |04rests in a V-shapedvtrough or plate |02 which extends between the two plates 94 and 96 at the bottom of the frame. The record strip 54 is drawn from the feed roll |04 up the front of the frame 36 over a. nat plate 06 and onto the wind-'up roll ||6, as is shown in Figure. 3. The angle between the sides of'trough |02 is suiiicient'to prevent -the feed roll |04I from rolling out of the frame 36 as the record strip unwinds and to provide suiicient frictlonito prevent it from unwinding except when pulled by rotation of the wind-up roll H6.

The plate |06 extends across the front of the frame 36 between the side plates 94 and 96 and forms a support behind the strip chart 64 to keep it iiat so that the pen will operate properly, and also so that manual inscriptions may be made on the chart if desired. 'Ihisplateis pivotally mounted at |08 near its upper end to the two side plates 94 and 96 and it extends downward almost to the bottom plate i102 leaving only a relatively narrow slot therebetween through which the strip chart is drawn so as to keep the strip chart feed roll in position and prevent it from being carried forward out of To insert ae new feed roll the bottom of plate it@ is pulled forwardly. Stops H0 limit its backward motion. The frame 36 is also provided with two latching levers ||8 pivoted to the side plates 94 and 96 by pivot pins 20 and havingv hooks |22 at their rearward ends to engage the frame member 34 to hold the record strip frame 36 in operative position. The wind-up roll H6 is provided with axles ||2 which are inserted in slots ||4 in theside plates 94 and 96 to rotatably support the roll |6 in its operating position so that it is iirmly pressed against the drive roll 86 when frame 36 is latched in position by means of levers H8.

As it frequently happens the dlnerent rolls of strip chart paper vary slightly in width, an adjustment spacing rod, generally indicated at |24, is provided to vary the spacing between the two guide plates 94 and 96. This member, shown in detail in Figure 4, comprises a rod |26 extending from plate 96 through plate 94 and provided at one end with a pivot pin |28joux'- nalled in a suitable bearing in plate 96, and an enlarged portion |30 near the other end threaded through a collar |32 attached to plate 94. A knurled knob |34 is-mounted on thevend of rod |26 extending through plate 94 whereby -it may be rotated to advance the threaded portion |30 through collar v|32 and thereby to adjust the space between plates 94 and 96. The method `Iused for making this adjustment when installing a new roll is to place the new roll in the position of wind-up roll ||6 and adjust the spacing rod |24 until the roll is lightly clamped between the guide plates 94 and 96. After this adjustment is made the new roll is placed in trough |02, the Wind-uproll replaced in slots ||4, and

'above invention and as many changes may be made in the embodiment above described, it is to be understood that all matter hereinbefore set forth as shown in the accompanying drawings is to be interpreted as illustrative only and not in a limiting sense.

I claim:

1. In apparatus for recording the deviation of a meter element from a control point, in v*combination, a rotatable member, means for transmitting the position of the meter elementto said member to cause it to assume positions of rotation corresponding to positions of deviation of the meter element, an effective bell crank pivoted about an axis below and parallel to the axis of rotation of said rotatable member and having a first arm mechanically connected to saidmember, having a second a'rm extending downwardly, a link dependent from a point in `approximately the same horizontal plane as the axis about which said bell crank rotates but laterally displaced therefrom, a pen rack swung from said second arm and said link, said bell crank and link being freely suspended 'in journals, and the connections l between the bell crank and the rotatable member and between the bell crank, the link and the pen rack being maintained substantially balanced whereby the pen rack is free to follow the movement of said rotatable member.

2. In apparatus for recording the position of a condition responsive element, ln combination, a pivotecl control member, means for transmitting the position of the condition responsive element to said control member to cause said member to y assume angular positions corresponding to positions of said element, a lever freely pivoted about a horizontal axis and having a driafng arm driven by said control member and a long arm extending downwardly, a link pivoted about an axis laterally displaced from and in approximately-the same horizontal plane as the axis of said lfe'v-er, a pen support hung between said long arm and said link, said lever and link being freely suspended in journals, and the gravitational forces acting on the connections between the lever andthe control member, and between the lever. the link and the pen support being substantially balanced whereby the pen support is free to follow the movement of said control member.

3. In apparatus for recording the position of a condition responsive element, in combination, a I

tosaid control member to cause said member to il u swung between said long arm and said second link whereby the pen support is free tovfollow the movement of said control member, and means to balance said eiective crank and the parts con nected therewith so that their center of gravity remains approximately at the axis of rotation throughout the range of operative movement.

4. In apparatus for recording the position of a condition responsive element, in combination, a pivoted control member, means for transmitting the position of the condition responsive element to said control member to cause said member to assume angular positions corresponding to the positions of said element, a lever having `three arms freely pivoted about a horizontal axis, the

rst arm of said lever being driven by said control member through a rst link, said second arm beinglong and extending downwardly, Said third arm extending from the axis of said lever away from said first and second arms, a second link pivoted about an axis laterally displaced from and in approximately the same horizontal plane as the axis of said lever, a pen support hung between said second arm and said second link whereby the pen support is free to follow thev movement of said control member, and a mass attached to said third arm to balance' said lever and the parts connected therewith so that the center of gravity thereof remains approximately at the axis of rotation throughout the range of operative movement.

' CUTI-IBERT J. BROWN. 

